The war on Ebola / Helen Barnswell

How the largest outbreak ever recorded prompted the development of two experimental vaccines and several promising treatments

Researchers often discuss the race between the Ebola virus and the people it infects. Patients only win the race if their immune system manages to defeat the virus before it destroys most of their organs. A community wins the race if it can isolate the first few patients before the disease spreads. Humanity will win the race if it develops treatments, and eventually vaccines, before allowing the virus to gain a permanent foothold in the world's cities.

For years the Ebola virus has had a natural advantage. The outbreaks were too small (typically less than a hundred people) and too short (less than five months) and researchers did not have the opportunity to test possible treatments. The threat was gone before the researchers could organize a clinical trial. It was difficult for the pharmaceutical companies and research groups to justify spending money on a disease, as terrible as it was, that in 40 years only killed 1,600 victims. Other diseases seemed far more worrisome: malaria, tuberculosis and AIDS killed more than three million people in 2013.

This rigid calculation changed with the recent horrific outbreak of Ebola in West Africa, the largest and longest ever. By the end of April 2015, at least 26,000 people had been infected with Ebola in Sierra Leone, Liberia and Guinea, and more than 10,800 deaths were attributed to the disease. Leading medical professionals in the world realized that not taking action would lead to the spread of the virus beyond the outbreak area. Therefore, an international response was required to identify and isolate the patients infected with Ebola, to build and staff dozens of emergency centers to treat them and to recruit enough burial teams to safely bury the dead.

This is the first time that scientists have encountered an Ebola outbreak large enough and long enough to enable vigorous clinical trials designed to find better treatments for an outbreak that cannot be stopped without developing new vaccines and drugs. They also won, for the first time, blanket agreement to test some experimental treatments on the battlefield. These unprecedented efforts may be more useful in dealing with the next Ebola outbreak than they are in the current epidemic. But if the researchers are successful this round, they can ensure that the Ebola virus never again has the upper hand when it strikes again (and it will).

A cunning killer

As horrifying as this seems, in view of the surge of cases in the last 15 months, there is a lack of information about the Ebola virus: where it lives, why it suddenly attacks humans and why more people don't get infected when it starts to spread. (On average, each individual in this outbreak transmitted the virus to one or two others, as opposed to highly contagious diseases like measles, where each patient typically infects an average of 18 others.)
Although Ebola is not one of the most contagious viruses, it is an incredibly effective killer of primates (apes) and humans. By the end of 2014, about 70% of people infected with the disease in West Africa had died, usually within days, and often unseen by health authorities.
The rate of progression and the degree of lethality of the disease in a particular person depend on two factors: the amount of viruses involved and the way in which they entered the body. After the first handful of viruses broke the biological species barrier to humans, probably from fruit bats, it didn't take long for the chain of infection to continue. Many Ebola victims were apparently infected after preparing sick bodies for burial. Another way to transmit viruses is when caregivers wipe the vomit from a patient's chin with their hands or clean up diarrhea from a sick child and then touch their own eyes, lips, nose or mouth. And if many viruses enter the bloodstream directly through an accidental needlestick injury, "I don't think anything can save that person," says Thomas Geisbert, a microbiologist at the University of Texas Medical Branch in Galveston. "He's just done."
Pathology reports and postmortems provide some of the best ways to learn about how the virus spreads inside the body, but few of these have been conducted on Ebola victims because of the high risk of accidental infection by the people performing the necessary invasive procedures. A new scientific survey identified only 29 patients in a 40-year history where autopsies were performed or samples were taken after death.
However, animal studies and pathological studies conducted so far show that the Ebola viruses land their first punch on the immune system. Like other viruses, the Ebola virus must harness the operating mechanisms of the cells it infects in order to reproduce. Among the initial targets are the dendritic cells, which usually serve as sentinels patrolling all body tissues, and the macrophages that digest damaged cells. Instead of trying to escape these first responders of the immune system, the Ebola viruses actually seek them out and start multiplying within them. This bold attack achieves two things: the viruses damage the ability of the cells to stimulate the other components of the immune system, and they catch a ride inside the cells and reach the lymph nodes, liver, spleen and other areas of the body without any difficulty.
And if this guerilla tactic is not enough, the Ebola virus uses another trick to hide its presence: it prepares a trap to distract the immune system. The virus forces the cells it infects to produce and release into the bloodstream a large amount of a substance called secreted glycoprotein ((sGP). The molecules of this substance are very similar to the molecules of another substance, glycoprotein (GP), which usually stand out from the outer envelope of viruses. Normally, the immune system latches onto the GP molecule and eliminates the virus associated with it. But the Ebola virus tricks the immune system and causes it to attack sGP molecules that are not attached to any virus, thus further undermining the body's ability to organize an effective defense.

new treatments

The recent outbreak of Ebola has taught doctors and health workers some practical ways to overcome the virus. It has long been known that despite the initial discrimination, the immune system can reorganize and defeat the virus provided it has enough time. Health care workers have realized in the current epidemic that they can buy patients some of the time needed by intravenously injecting fluids as soon as the first symptom appears. The World Health Organization has approved treating some patients with blood taken from surviving patients, which by definition must contain many antibodies, although no one knows if the treatment is effective.
The risk taken by the decision to use a previously untested treatment shows the great desperation that prevailed in West Africa. But there was at least theoretical logic in the approach. Serum from convalescents was used successfully as a treatment for polio from the 20s to the 50s and as a treatment for influenza in the 20 global pandemic. The Bill and Melinda Gates Foundation has begun funding clinical trials of serums against Ebola in hard-hit Guinea.
Of course, thanks to the biotechnological revolution, scientists can now produce the desired antibodies artificially and they did so with a preparation called ZMapp, which was prepared from three monoclonal antibodies directed against the Ebola virus. The ZMapp preparation gained ground-breaking status in the summer of 2014 when Kent Brantley, an American missionary doctor who contracted Ebola in Liberia, was the first to receive the treatment. The media reported that Brantley, who was seriously ill when he received the first infusion, recovered quickly and took a shower on his own the next day. There were less than a dozen treatment doses when Brantley was treated (each dose includes three infusions), and within a few weeks even that small amount was used up.
When the outbreak began, ZMapp was in the early stages of development, the animal testing phase, and had not yet begun commercial scale production. Since then, the rate of production of the drug has increased with the hope that the clinical trials in West Africa will begin in the first quarter of 2015. But even if the trials prove the effectiveness of the drug, there is no chance that there will be a sufficient amount of ZMapp for all the needs in the near future.
In fact, even this amount of the drug would not have been in the hands of the doctors if the governments were not afraid that the Ebola virus would become a biological weapon and therefore began to invest money in the development of antibodies. Scientists at the Canadian Laboratory of Microbiology and the American Institute of Allergy and Infectious Diseases (NIAID) researched and developed the antibodies in the cocktail and sold the production rights to the Mapp Biopharmaceutical company, which in turn entrusted the cultivation of the antibodies in genetically engineered tobacco plants to the Kentucky BioProcessing company. The latter can produce enough antibodies for 17 to 25 treatment doses in each batch. It takes 12 weeks to grow the plants and a few more weeks to produce the material.

Efforts are being made to significantly speed up ZMapp output. The US government, through the Public Health Emergency Management Agency, is considering adding a manufacturer in a move that could increase ZMapp output four or five times. Also, researchers are conducting studies in primates to determine if it is possible to lower the number or volume of transfusions and thus expand the supply.

A vaccine component is required

A very long time was lost in the first phase of the spread of Ebola in West Africa until they recognized its true extent and realized that the epidemic had split into dozens of different tiny outbreaks, each with its own characteristics. Aid workers, military personnel and local communities are making supreme efforts to save lives and curb the disease. But experts fear that as the epidemic continues, the risk increases that the world will find itself facing a persistent Ebola infection in West African enclaves. Also, the paralyzing effect of the virus on the health systems in the infected countries, can open the door to other public health crises, such as outbreaks of measles or even the resurgence of polio.
One of the best ways to prevent such a bleak future is to develop, test and distribute a successful component, which was impossible in the previous smaller and shorter outbreaks. When the number of cases in Guinea, Liberia and Sierra Leone skyrocketed in the summer of 2014, the bodies determining the international response determined that an effective vaccine could be the only means of stopping the epidemic.
Safety studies of the two leading vaccine components, marked with the codes cAd3-EBO and rVSV-ZEBOV, were conducted at the end of 2014 in several hundred volunteers in the USA, Canada, Europe and several unaffected countries in Africa. Larger studies involving thousands of people are scheduled to begin in 2015 in Liberia and Sierra Leone, followed by trials in Guinea.
The pace is unprecedented: work that normally takes five to ten years and includes testing and large-scale production of a component, takes place in less than a year. And yet, as the overall rate of new infections began to decline in Liberia toward the end of 2014, a new dilemma emerged: Will there be enough patients to determine whether the compound is working?
None of those involved in the eradication of Ebola are interested in seeing more cases. But in vaccine studies, the only way to find out if the experimental drugs work is when the pathogen spreads. If the infection rate drops too low, the clinical trial intended for 27,000 people in Liberia will have to expand, and this will add to the cost, complexity and time required to get answers.
The organizers still hope to prevent this, says Charles Link Jr., CEO of NewLink Genetics, a biotech company in Iowa in the US that is developing rVSV-ZEBOV in collaboration with the biotech giant Merck. The plan is to focus on areas in Liberia where the pollution rate is higher than average. Nothing is easy when it comes to the Ebola vaccine project, says Link, "The complexity is much greater than usual."
The NewLink component was designed by scientists at the Public Health Agency of Canada. It consists of genetically modified live viruses of another disease (the VSV virus that causes inflammatory blisters in the mouth) to which is attached part of a protein common on the surface of Ebola viruses. The VSV virus causes disease in domestic animals, but not in humans. In the vaccine component, the virus causes a mild infection that stimulates the immune system to produce antibodies against the Ebola protein attached to it, but the component cannot trigger the disease itself.

The second component, cAd3-EBO, was originally developed by scientists at NIAID. The Glasgow Smith Klein company acquired the rights after buying the Okairos company in 2013, a Swiss company for the development of vaccine components. This is a component that uses killed adenoviruses from chimpanzees that have been genetically engineered to present key proteins from the surface of the Ebola virus to the immune system.
Both of these components have advantages and disadvantages. The Glaxo-Smith-Kline component began its journey after undergoing more advanced testing than the NewLink component. But the VSV component is easier to produce and in late December 2014 there were many more batches of this component available. The exact amount of the doses depends on the results of the experiments to check the dose needed to produce good levels of antibodies.

There is concern that one dose of the Glaxo-Smith-Kline ingredient will not be enough to protect the patient. But the method in which two doses are given, and especially the one in which different components are given for initialization and amplification, is very difficult to implement in the affected countries in view of the state of their health infrastructure. One dose of the NewLink ingredient is expected to be sufficient, but it can cause mild (though certainly confusing) side effects such as low fever, chills, muscle aches or headaches, that is, in other words, exactly the same symptoms that are taught about contracting Ebola. In a world where these symptoms are used to identify Ebola patients, such side effects will make it difficult to distinguish sick from healthy people in outbreak areas.
The experiment in Liberia is planned to include three groups. The participants in one group will receive the Glaxo-Smith-Kline compound, the second group will receive the NewLink compound and the third group will receive a dummy compound (placebo): an anti-influenza or anti-jaundice type B compound. Several prominent scientists have claimed over the pages of the Lancet and elsewhere that controlled trials Placebos in this situation are not ethical. But the US Food and Drug Administration (FDA), which has to approve any drug intended for use by the military or health organizations, pushed in the direction of placebo-controlled trials. "We need to learn what helps and what hurts as quickly as possible and in the most defined way," says Luciana Borrio, who is responsible for the FDA's handling of the Ebola issue. "It will be important for future generations and we have to do it the right way."
Jeremy Ferrer, director of the British Wellcome Charitable Foundation, which finances several drug and ingredient trials, expected more innovative approaches: step-wedge clinical trials or trials in which groups are randomized rather than individuals, allowing, in the end, for each get the active ingredient. And yet he is also willing to accept placebo-controlled trials. "I'm not satisfied with it," he says. "But when it comes to a compound that is given to healthy people, when its safety profile and effectiveness are not known, I can actually accept either the randomization of groups or the staggered design, or a placebo-controlled trial."
Meanwhile, a randomized clinical trial will be conducted in Sierra Leone. The experimental design relies on the fact that it is not possible to vaccinate everyone at once to create a control group. For this reason, the proportion of new patients in areas that have already received the vaccine is compared to areas that have not yet been vaccinated. The advantage: everyone will get the ingredient. The downside: the longer time it takes to determine if the component is working.
An experiment of some kind will also be conducted in Guinea, although apparently it will be less ambitious. The infrastructure in this country is worse than in its neighbors, which makes it even more difficult to conduct experiments. Marie-Paule Kinney, who directs international efforts at the World Health Organization (WHO) to develop components and drugs for Ebola, says that in the trial in Guinea, all relief workers will be vaccinated in an observational study without the use of a placebo. It is also possible that the Gates Foundation will finance an experiment in which the effectiveness of a ring vaccine will be tested, that is, the vaccination of the people in the immediate vicinity of the patient in an attempt to prevent further spread. (It was the ring vaccine that ultimately defeated smallpox in the 20th century.)
Series of other experimental components are now in various stages of development. Some of the ingredients are considered at least as promising as the Glaxo-Smith-Kline and NewLink products. A component manufactured by Johnson & Johnson has been in the safety trial phase since the beginning of January 2015. However, those who follow the components of Glaxo-Smith-Kline and NewLink are facing a harsh economic reality. In the race to defeat the deadly virus, fourth and fifth place are not taken into account. The future market for anti-Ebola compounds will be limited. The World Health Organization or GAVI, (International Society for Vaccines) will probably keep the product to be used in future outbreaks. And some rich countries will surely buy supplies as a preventive measure against biological terrorism. But the market will probably not be bigger. So if the leading manufacturers do not fail, the manufacturers behind the two will probably fail. "They will only have a place if the first two fail," says Kinney.
It is clear that the Ebola research scientists and public health officials are considering the possibility that all efforts to obtain a vaccine may be in vain. Although the epidemic is no longer growing exponentially, as it was in September 2014, the outbreak is still not under control. The number of new cases has decreased in many parts of Liberia, but disease transmission is still strong in the western and northern provinces of Sierra Leone. As long as the number of new cases does not drop to zero, the possibility of regeneration, resurgence and spread of the disease is still valid.
Thousands of people died in 2014. And unfortunately, despite the tireless efforts of health workers, burial teams and volunteers, hundreds and even thousands more will die in 2015. But in the coming months the world can get a sense of how much faster and how much further we need to move to get ahead of this despicable virus.

on the notebook
Helen Branswell is a Canadian News Agency medical reporter. Her interest in new diseases began when she covered the SARS epidemic in 2003.
in brief

• As long as the Ebola outbreaks remained small and scattered, there was no real opportunity for scientists to test and disseminate better vaccine formulations or treatments.
• The latest outbreak in West Africa, the largest ever recorded, changed the situation, focusing new attention and resources on the fight against the brutal killer.
• Researchers are rushing to test some experimental treatments and potential ingredients in hopes of preventing thousands more deaths.

What is the Ebola virus?
Belongs to the family of filoviruses (Filoviridae) so called because of their filamentous shape. The Ebola virus consists of one strand of RNA to which proteins are attached and is wrapped in a fatty membrane. Scientists have so far isolated two members of the family, the Ebola and Marburg viruses, and grown them in culture. Scientists have sequenced some genes from a third member of the family, Lloviu virus, but the virus itself has not yet been fully characterized in the laboratory. Of the five known strains of Ebola (below), Reston is the only one that does not cause disease in infected people.
More on the subject
Ebola: What You Need to Know. In-Depth Reports, Scientific American.com; August 5, 2014.
Camouflage and Misdirection: The Full-On Assault of Ebola Virus Disease. John Misasi and Nancy J. Sullivan in Cell, Vol. 159, no. 3, pages 477-486; October 23, 2014.
www.cell.com/cell/pdf/S0092-8674(14)01293-8.pdf
Reports on the Ebola situation from the World Health Organization

The article was published with the permission of Scientific American Israel